A data processing environment comprises a variety of hardware, software, and firmware networking components. A physical network, also called an underlay, is a network defined using such components.
Techniques are available presently to construct a logical network, also known as a software defined network (SDN) overlay (hereinafter “overlay,” “overlay network,” or “OVN”), from such networking components. Essentially, networking components are abstracted into corresponding logical or virtual representations, and the abstractions are used to define the overlay. In other words, an overlay is a logical network formed and operated using logical representations of underlying networking components.
Physical networks usually exist within the demarcated boundary of the data processing environment whose networking components are utilized in the physical network. Unlike a physical network, an overlay can be designed to span across one or more data processing environment. For example, while a physical network may be contained within a datacenter, an overlay may span across one or more datacenters.
As an example, a logical representation of a networking gateway can participate in an overlay, such that a function attributed to the logical representation of the networking gateway in the overlay is actually performed by the underlying networking gateway component in the underlay.
In an overlay, because the actual networking components that perform the networking functions are abstracted into logical entities representing the networking functionality offered by those components and not the actual implementations of those functionalities, something is needed to direct that networking functionality into a functioning logical network. An SDN controller is a component that manages and operates the logical networking components within an overlay.
A virtual machine (VM) comprises virtualized representations of real hardware, software, and firmware components available in a data processing system. The data processing system can have any number of VMs configured thereon, and utilizing any number of virtualized components therein. The data processing system is also referred to as a computing node, a compute node, a node, or a host.
In large scale data processing environments, such as in a data center, thousands of VMs can be operating on a host at any given time, and hundreds if not thousands of such hosts may be operational in the data center at the time. A virtualized data processing environment such as the described data center is often referred to as a “cloud” that provides computing resources and computing services to several clients on an as-needed basis.
A virtual switch, sometimes herein referred to as a vSwitch, is a software application that allows communication between VMs. A virtual switch is completely virtual and can connect to a network interface card (NIC). A virtual switch merges physical switches into a single logical switch. This helps to increase bandwidth and create an active mesh between servers and switches. A virtual switch may be embedded into a server's installed software or included in a server's hardware as part of its firmware.
Network virtualization by defining overlay networks is an emerging trend in the management and operation of data centers and cloud computing environments. One of the goals of network virtualization is to simplify the network provisioning in multi-tenant data processing environments, as well as dedicated customer data processing environments.
Unicasting is a method of sending data point-to-point, to wit, from a single sender to a single receiver. Broadcasting is a method of sending the same data to all possible destinations. Another multi-destination distribution method, multicasting, sends the same data only to interested destinations called receivers by using special address assignments. Internet Protocol (IP) multicast is the process of multicasting IP packets to several receivers in a single transmission of the IP packet. IP multicast is a popular technique used to help conserve bandwidth in the data center and reduce the load on servers.
IP multicast operating in an overlay network is called overlay multicast. Overlay multicast can be achieved in different ways, depending on the support for multicasting provided in the underlay network. Multicast based overlay multicast requires the underlay network to provide support for multicasting. Multicasting in underlay networks is not presently prevalent in data processing environments. Multi-unicast based overlay multicast is a method to transmit multicast packets in the overlay network where the underlay supports unicasting but does not support multicasting.